Studies of origin and distribution of persistent environmental organochlorine (OC) pollutants in Croatia have comprised three groups of compounds: OC pesticides, polychlorinated biphenyls (PCB), and more recently polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). The use of OC pesticides in Croatia is restricted, and hexachlorobenzene is even forbidden. PCBs may be used in closed systems only. The main source of PCDD/PCDF in the environment is combustion, but these also occur as byproducts in certain pesticide and other chemical formulations. Common to all those compounds are high hydrophobicity, poor solubility in water, and low volatility. They are rapidly and strongly sorbed by most soils and are often associated with bottom sediments in aquatic systems. Circulation of air masses, precipitation of particles onto which pollutants are sorbed, and wet depositions washing them out from the atmosphere may transport OC pollutants over long distances. The levels of persistent OC micropollutants in Croatia were investigated in surface, ground, and drinking water, sea water, river and marine sediments, soil, air, wet depositions, and coniferous tree needles. Most data collected for the last 20 years concern regular or periodical determination of OC pesticides in water. The most often detected compounds were p,p’-DDT and its metabolites, -hexachlorocyclohexane ( -HCH), and hexachlorobenzene. Recent measurements show that the concentrations of OC pesticides in different waters keep within the range of ecotoxicologically acceptable and legally prescribed values. The highest PCB levels (>100 ng/dm3) were measured in source and surface waters in karst areas where elimination of water pollutants by natural filtration through soil layers was almost negligible. The data on persistent OC compounds in soil and sediments are rare although, due to sorption and bioconcentration tendency, OC compounds are more likely to show higher levels in these media than in water. The most frequently detected OC pesticides in soils/sediments were the DDT-type compounds and -HCH. In most analysed soils and sediments PCB mass fractions were characteristic for global environmental pollution. Higher PCB levels were determined in soils collected in the close vicinity of transformer stations, in the airport areas, and close to some industrial plants. PCDD/PCDF levels in the airport soil kept within the range typical for urban and rural areas, whereas they rose by about 50 times in soils collected near a chloralkali electrolysis plant. Traces of OC pesticides and PCB were detected in wet depositions collected in urban and rural areas. The rain and snow samples collected in Zagreb contained traces of PCDD/PCDF and the highest concentrations at pg/dm3 level were measured for octa-CDD. The only data on OC pesticide, PCB and PCDD/PCDF levels in the ambient air were reported for air samples collected in 1997 and 1998 in the Zagreb city area. The highest pesticide concentrations were measured for -HCH. The highest PCDD/PCDF level was determined in the industrial zone of the city. The level of environmental pollution in a certain location can be evaluated through measurement of OC compounds in coniferous tree needles. All needle samples collected in the 1991–1998 period in different regions of Croatia contained OC pesticides and PCB. The mass fraction ratio _-HCH/_-HCH<1 found by the analysis of needle, air, and rain samples confirmed recent release of lindane in the environment as a consequence of its frequent local usage. Istraživanja podrijetla i raspodjele postojanih organoklorovih (OC) spojeva u okolišu u nas uključuju organoklorove (OC) pesticide, poliklorirane bifenile (PCB), poliklorirane dibenzop- dioksine (PCDD) i poliklorirane dibenzofurane (PCDF). Njihove razine ispituju se u površinskim, podzemnim i pitkim vodama, moru, riječnim i morskim sedimentima, tlu, zraku, oborinama te iglicama crnogoričnog drveća. U vodama su u proteklih dvadesetak godina najčešće detektirani pesticidi bili p,p’-DDT i njegovi metaboliti, gama-heksaklorcikloheksan (gama-HCH) i heksaklorbenzen. Najviše razine PCB-a izmjerene su u vodama krškog područja. Malobrojni podaci o OC spojevima u tlu/sedimentima upućuju na povišene razine PCB-a u tlu uz oštećene trafostanice i unutar zračnih luka. Razine PCDD-a i PCDF-a oko 50 puta više od onih tipičnih za seoska i urbana područja izmjerene su u tlu neposredno uz postrojenje kloralkalne elektrolize. OC pesticidi i PCB-i detektirani su u oborinama i zraku na području Zagreba te u iglicama crnogoričnog drveća na različitim lokacijama. Uočen je skorašnji unos gama-HCH i p,p’-DDT-ja u atmosferu. Najviše razine PCDD/PCDF-a u zraku na području Zagreba izmjerene su u industrijskom dijelu grada.